Analysis of atomic magnetometry using metasurface optics for balanced polarimetry.

Atomic magnetometry is one of the most sensitive field-measurement techniques for biological, geo-surveying, and navigational applications. An essential process in atomic magnetometry is measurement of optical polarization rotation of a near-resonant beam due to its interaction with atomic spins under an external magnetic field. In this work, we present the design and analysis of a silicon-metasurface-based polarization beam splitter that have been tailored for operation in a rubidium magnetometer. The metasurface polarization beam splitter operates at a wavelength of 795 nm and has a transmission efficiency > 83% and a polarization extinction ratio > 20 dB. We show that these performance specifications are compatible with magnetometer operation in miniaturized vapor cells with sub-picotesla-level sensitivity and discuss the prospect of realizing compact, high-sensitivity atomic magnetometers with nanophotonic component integration.

Continuing Medical Education Questions: February 2021.

Article Title: The Role of Noninvasive Tests in Clinical Gastroenterology Practices to Identify Patients With Non-Alcoholic Steatohepatitis at High Risk for Adverse Outcomes: Expert Panel Recommendations.

Continuing Medical Education Questions: January 2020.

Article Title: ACG Clinical Guideline: Disorders of the Hepatic and Mesenteric Circulation.

Continuing Medical Education Questions: June 2019.

Article Title: Sclerosing Mesenteritis.

Continuing Medical Education Questions: February 2019.

To receive CME/MOC credit for this activity, please go to: http://acgjournalcme.gi.org/Article Title: Opportunities to Prevent Alcoholic Liver Cirrhosis in High-Risk Populations: A Systematic Review and Meta-Analysis.

Stereotactic Body Radiation Therapy for Prostate Cancer: An Institutional Experience Using MRI-guided Treatment Planning.

With 222,500 new cases estimated for 2017, prostate cancer makes up approximately 10% of all new cancer diagnoses in the United States and is the third most common cancer after breast and lung cancer. In 2013, the American Society of Radiation Oncology (ASTRO) policy model recognized that stereotactic body radiation therapy (SBRT) may be used as an alternative to standard treatment modalities, i.e. intensity modulated radiation therapy (IMRT), to treat prostate cancer. In this study, we report outcomes for a cohort of 30 patients with prostate cancer treated with SBRT at our institution. We also describe, in detail, the technical aspects of SBRT planning and delivery for these patients, specifically the use of MRI in determining treatment volumes and detecting gross lesions. After institutional review board (IRB) approval, a retrospective analysis was done of 30 males with the diagnosis of prostate cancer treated in the Department of Radiation Oncology at the Baylor College of Medicine between January 2011 and June 2016. All patients received image-guided SBRT. Treatment planning was performed using a non-contrast computed tomography (CT) scan as well as a contrast thin-slice open MRI with the patient in the treatment position. Patient comparisons were done using the Mann-Whitney U, Fishers Exact, and Kaplan-Meier tests. Thirty patients were treated between January 2011 and June 2016. Twenty-six had follow-up data available and were included in the analysis. Median follow-up was 32 months (range 2-72 months). Mean and median ages at diagnosis were both 68.5 years. A total of 64% of the patients had foci on magnetic resonance imaging (MRI) or a palpable nodule on an exam. The median prostate-specific antigen (PSA) at diagnosis was 7.35 ng/mL (range 2.8-13), and the median PSA nadir after treatment was 0.4 ng/mL (range 0.01-4.5). The biochemical disease-free recurrence rate per Phoenix definition was 96%, with only one patient experiencing a biochemical recurrence four years after treatment. The patient with a recurrence was T2c, high-intermediate risk with a Gleason score of 7(3+4). He had a focus visible on MRI. Overall survival was 96%, with the only patient death unrelated to his prostate cancer. There was no statistical significance associated with recurrence and nodule on MRI (p=0.318), T-stage (p=0.222), Gleason score (p=0.890), risk group (p=0.654), age (p=0.692), or race (p=0.509). There were no grade three or four acute or long-term toxicities. SBRT of the prostate is an effective method for treating prostate cancer. We saw excellent PSA control and minimal acute or long-term toxicities after a median of three years of follow-up.

Building resilience and adaptation to manage Arctic change.

Unprecedented global changes caused by human actions challenge society's ability to sustain the desirable features of our planet. This requires proactive management of change to foster both resilience (sustaining those attributes that are important to society in the face of change) and adaptation (developing new socioecological configurations that function effectively under new conditions). The Arctic may be one of the last remaining opportunities to plan for change in a spatially extensive region where many of the ancestral ecological and social processes and feedbacks are still intact. If the feasibility of this strategy can be demonstrated in the Arctic, our improved understanding of the dynamics of change can be applied to regions with greater human modification. Conditions may now be ideal to implement policies to manage Arctic change because recent studies provide the essential scientific understanding, appropriate international institutions are in place, and Arctic nations have the wealth to institute necessary changes, if they choose to do so.

Kinetic modeling of beta-chloroprene metabolism: II. The application of physiologically based modeling for cancer dose response analysis.

beta-Chloroprene (2-chloro-1,3-butadiene; CD), which is used in the synthesis of polychloroprene, caused significant incidences of several tumor types in B6C3F1 mice and Fischer rats, but not in Wistar rats or Syrian hamsters. This project investigates the relevance of the bioassay lung tumor findings to human health risk by developing a physiologically based toxicokinetic (PBTK) model and exploring a tissue specific exposure-dose-response relationship. Key steps included identification of the plausible genotoxic mode of action, experimental quantification of tissue-to-air partition coefficients, scaling of in vitro parameters of CD metabolism for input into the PBTK model, comparing the model with in vivo experimental gas uptake data, selecting an appropriate tissue dosimetric, and predicting a corresponding human exposure concentration. The total daily milligram amount of CD metabolized per gram of lung was compared with the animal bioassay response data, specifically combined bronchiolar adenoma/carcinoma. The faster rate of metabolism in mouse lung agreed with the markedly greater incidence of lung tumors compared with the other rodent species. A lung tissue dose was predicted for the combined rodent lung tumor bioassay data at a 10% benchmark response. A human version of the PBTK model predicted that the lung tissue dose in humans would be equivalent to continuous lifetime daily exposure of 23 ppm CD. PBTK model sensitivity analysis indicated greater dependence of model predictions of dosimetry on physiological than biochemical parameters. The combined analysis of lung tumor response across species using the PBTK-derived internal dose provides an improved alternative to default pharmacokinetic interspecies adjustments for application to human health risk assessment.